This prospective observational study evaluates the burden of Atrial High-Rate Episodes (AHRE) in patients without a prior history of atrial fibrillation who undergo concurrent Bachmann Bundle Area Pacing (BBAP) and Left Bundle Branch Pacing (LBBP). Physiological pacing at these sites aims to improve interatrial conduction and reduce the risk of atrial arrhythmias.

The study includes a comparative assessment across three patient groups:

1. BBAP + LBBP (physiological pacing group)
2. Right Atrial Appendage (RAA) pacing + LBBP
3. Conventional pacing - RAA and Right Ventricular (RV) pacing AHRE burden will be quantified via device diagnostics and remote monitoring at 3, 12 and 24 months post-implantation. Episodes will be classified by duration (0-6 min, 6-24 h, >24 h), differentiating subclinical AHRE from clinically documented AF.

Secondary analyses include electrocardiographic changes (P-wave indices), the need for antiarrhythmic therapy, and comprehensive echocardiographic evaluation of atrial function (e.g., LA strain, conduction delays, LAVI).

The study aims to determine whether physiological pacing (BBAP + LBBP) provides superior protection against AHRE development compared with RAA + LBBP and conventional pacing strategies.

Atrial high-rate episodes (AHRE) detected by cardiac implantable devices are associated with an increased risk of developing atrial fibrillation (AF), stroke, and atrial remodeling. Traditional right atrial and right ventricular pacing may alter atrial activation patterns, potentially promoting electrical and structural changes that predispose to atrial arrhythmias.

Physiologic pacing strategies targeting the Bachmann bundle region and the left bundle branch have emerged as alternatives designed to preserve normal conduction pathways. Bachmann Bundle Area Pacing (BBAP) facilitates more synchronous biatrial activation, while Left Bundle Branch Pacing (LBBP) results in near-physiologic ventricular activation. Both methods may reduce conduction delays and improve atrial and ventricular electromechanical function.

This prospective observational study examines whether physiologic atrial and ventricular pacing reduces the burden of device-detected AHRE compared with commonly used pacing configurations. Three groups are evaluated: (1) BBAP combined with LBBP, (2) right atrial appendage pacing combined with LBBP, and (3) conventional right atrial and right ventricular pacing. All enrolled participants have a clinical indication for permanent pacing and no prior diagnosis of AF.

AHRE burden will be assessed through routine device diagnostics and remote monitoring over a 24-month follow-up. Electrocardiographic and echocardiographic data will also be collected to explore relationships between conduction patterns, atrial function, and arrhythmia occurrence. The study aims to clarify whether preserving physiologic conduction pathways influences long-term AHRE burden and may contribute to AF prevention in paced patients.

Inclusion Criteria:

• Adult patients (≥ 18 years) with a clear indication for permanent pacing, according to ESC guidelines [15] for the management of conduction disturbances (e.g. symptomatic bradycardia, complete atrioventricular block, sinus node dysfunction).
• Sinus rhythm at the time of implantation, with no documented episodes of atrial fibrillation prior to implantation, either in the medical history or in previous recordings (ECG, Holter, telemetry).
• Ability to be followed up for at least 24 months after implantation.
• Provision of written informed consent to participate in the study.

Exclusion Criteria:

• History of atrial fibrillation prior to implantation, either permanent or paroxysmal, documented on ECG, Holter, or telemetry.
• Prior pharmacological or interventional treatment for AF (e.g. antiarrhythmic drugs, catheter ablation).
• Inability to comply with long-term follow-up or non-adherence to follow-up visits.
• Contraindications to pacemaker lead placement at the selected sites.
• Participation in another study that could influence the results.
• Previous device implantation.

Adult patients (≥ 18 years) with a clear indication for permanent pacing, according to ESC guidelines [15] for the management of conduction disturbances (e.g. symptomatic bradycardia, complete atrioventricular block, sinus node dysfunction).